Fiber optic cables include optical fibers which transmit signals for cable television, computer, and telephone networks. Fiber optic cables are used in indoor and outdoor environments. The outdoor environment exposes the cable to the possibility of being flooded, or otherwise submerged in water. If the cable has leak-paths caused by fatigue, rodents or otherwise, the migration of water in the cable may cause failure of the cable components. Moreover, longitudinal water migration within the cable may cause the cable to act as a conduit, thereby flooding rooms or compartments to which the cable runs.
Fiber optic cables may be subjected to extrinsic compressive forces, for example, from cable support clamps or, for buried cable, the weight of earth and stone. A given cable must be robust enough to withstand such extrinsic forces. In the event that water migrates through the cable, or the cable experiences an overload of compressive forces, the ability of the optical fibers to transmit signals may be reduced or altogether eliminated.
To ensure that fiber optic cables are protected, cable components have been developed to inhibit water migration and to resist compressive forces. Such features comprise a water impermeable medium for inhibiting water migration, and compressive strength members for increasing the crush strength of the cable. Water impermeable mediums, also known as flooding compounds, generally comprise a greasy or jelly-like substance which is applied in the interstices between components inside the cable. However, where fibers in the cable are to be terminated to a connector or the cable network is to be modified, the craftsman must remove the flooding compound from the cable components with chemical de-greasing agents. This is a potentially messy and a time-consuming process, especially in taught sheath, mid-span access operations. Moreover, manufacturing processes designed to apply the flooding compound to the cable components may be unsuccessful in completely filling each interstice, thereby leaving the possibly of water migration through non-filled interstice portions. To compound the problem, where compressive strength members are used the compressive strength members will generally increase the number of non-filled interstice portions.
Examples of conventional fiber optic cables are disclosed in GB Patent Specification 1601004, some of which cables include compressive strength members. In the examples where compressive strength members and a water impermeable medium are used in combination there are isolated non-filled interstice portions. Moreover, the recommended water impermeable medium is petroleum jelly, which, as noted above, is a messy and time-consuming substance to remove.